1. Field of the Invention
Embodiments of the present invention generally relate to conserving power when driving voltages onto source lines in a display screen, and more specifically, to precharging a source driver using a latent voltage on a source line.
2. Description of the Related Art
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones).
Display panels in input devices typically use source drivers to update the voltage across individual pixels. For example, each source driver may be coupled to multiple source lines. As the source driver iterates between the source lines, the driver may output different voltages for each of the source lines. Moreover, the source lines may already have been charged to a particular voltage from a previous frame update. As the source driver slews from a voltage used to set one source line to another voltage used for setting the voltage on the next source line, the driver may consume power unnecessarily by both decreasing and increasing the voltage already stored on the source line from the previous update.
Therefore, there is a need for ensuring that when updating a source line, the source driver either increases the previous voltage stored on the source line or decreases the previous voltage stored on the source line, but not both.